An automatic sprinkler system is one of the most widely used devices for fire protection. These systems have sprinklers that are activated once the ambient temperature in an environment, such as a room or a building, exceeds a predetermined value. Once activated, the sprinklers distribute fire-extinguishing fluid, preferably water, in the room or building. A fire sprinkler system, depending on its specified configuration, is considered effective if it controls or suppresses a fire.
The sprinkler system can be provided with a water supply (e.g., a reservoir or a municipal water supply). Such supply may be separate from that used by a fire department. Regardless of the type of supply, the sprinkler system is provided with a main that enters the building to supply a riser. Connected at the riser are valves, meters, and, preferably, an alarm to sound when the system activates. Downstream of the riser, a usually horizontally disposed array of pipes extends throughout the fire compartment in the building. Other risers may feed distribution networks to systems in adjacent fire compartments. The sprinkler system can be provided in various configurations. In a wet-pipe system, used for example, in buildings having heated spaces for piping branch lines, all the system pipes contain a fire-fighting liquid, such as, water for immediate release through any sprinkler that is activated. In a dry-pipe system, used for example, in unheated areas, areas exposed to freezing, or areas where water leakage or unintended water discharge is normally undesirable or unacceptable such as, for example a residential occupancy, the pipes, risers, and feed mains, branch lines and other distribution pipes of the fire protection system may contain a dry gas (air or nitrogen or mixtures thereof) under pressure when the system is in a stand-by or unactuated condition. A valve is used to separate the pipes that contain the water. When heat from a fire activates a sprinkler, the gas escapes from the branch lines and the dry-pipe valve trips or actuates; water enters branch lines; and fire fighting begins as the sprinkler distributes the water.
There are patent publications which describe the control and monitor of dry type residential fire sprinkler protection systems. For example, U.S. Patent Publication No. 20080277125; U.S. patent application Ser. No. 11/916,419, entitled “Releasing Control Unit for Residential Fire Protection System,” which is incorporated herein by reference in its entirety.
U.S. Patent Publication No. 20080277125 describes an electronically operated solenoid fluid control valve for separation of the dry and wet portions of the fire protection system. It may be desirable to have a mechanically operated control valve option or alternative, in which for example, the pressure of gas in the dry sprinkler piping holds the control valve in closed state against an inlet of liquid (water) pressure. One type of mechanically operated dry pipe control valve is shown and described in U.S. Pat. No. 7,814,983 (the '983 patent). The dry pipe valve of the '983 patent more specifically shows and describes a clapper that pivots about a pivot axis from a closed or sealed position against a valve seat to an open position angled away from the valve seat. The pivot-type valve is further described as having a valve arrangement in that can be maintained in a sealed, occluded or closed state when the ratio of inlet water pressure below the clapper to gas pressure above the clapper is at a minimum 5.5. Accordingly, the valve is tripped, actuated or operated when the ratio is less than 5.5.